SQL Queries with Full Values
含有全部值语义的SQL查询

SQL phrases require the use of predicate NOT EXISTS to construct complicated nested query in order to express the full value meaning. Practitioners find it very difficult to write and easy to make errors. Tuple relational calculus can fully express such meaning. This paper uses examples to discuss and demonstrate trans formation rules when trans forming a tuple rel ational calculus expression to a SQL query, which is very helpful to SQL query learners.